How can I determine the order of the product specifications?

The product specifications of a product are displayed in the order that is indicated by rank when the product is added in via the API. The moment a product is (automatically) placed in an e-mail, the order of the products can immediately be viewed.

Incidentally, it is not required to have a rank added to product specifications when launching a product. If you omit it from a product specification, then this product specification gets the default value of 0 (zero) as a rank. If you omitted them from all the product specifications of a product, then they would all get the value of 0. The order in which the product specifications are then displayed is the order in which they are added to the database.